Large-area Ag2Sb-AgTe transverse heterojunction and preparation method and application thereof

Abstract

The invention relates to the technical field of heterojunction preparation, in particular to a large-area Ag2Sb-AgTe transverse heterojunction and a preparation method and application thereof.The preparation method includes the steps that sputtering treatment is conducted on a silver substrate, and heating and heat preservation are conducted on the silver substrate to obtain a silver single crystal substrate; evaporating and depositing tellurium powder to obtain a silver single crystal substrate deposited with tellurium clusters; carrying out first-time temperature rise heating and heat preservation treatment to obtain a substrate deposited with tellurium-silver alloy; evaporating and depositing antimony powder to obtain a substrate deposited with antimony clusters and tellurium-silver alloy; and carrying out secondary temperature rise heating and heat preservation treatment to obtain the large-area Ag2Sb-AgTe transverse heterojunction. The Ag2Sb-AgTe transverse heterojunction hetero-edge structure prepared by the above steps has a large area, the area is greater than 100 nm < 2 >, and the Ag2Sb-AgTe transverse heterojunction hetero-edge structure is a planar six-membered ring structure formed by Ag2Sb and AgTe and connected by covalent bonds and has no by-product.

Description

Technical Field

[0001] This invention relates to the field of heterojunction fabrication technology, and in particular to a large-area Ag2Sb-AgTe lateral heterojunction, its fabrication method, and its applications. Background Technology

[0002] Among numerous technological approaches, two-dimensional heterojunctions, especially lateral heterojunctions intrinsically linked by chemical bonds, can achieve seamless connectivity of different semiconductor materials within a single atomic layer. This structure effectively avoids the interface contamination and lattice mismatch problems of traditional mechanically stacked heterojunctions, forming a steep and clean interface, thereby significantly improving carrier transport efficiency and opening up new avenues for bandgap engineering and functional integration at the single atomic level. Currently, the widely studied two-dimensional lateral heterojunctions are mostly based on transition metal chalcogenides, but their material systems are relatively limited, and they suffer from problems such as insufficient carrier mobility and limited bandgap tuning range, which restricts their application in a wider range of fields.

[0003] Silver telluride (AgTe), a typical transition metal chalcogenide material, possesses a direct band gap of 0.95 eV. Due to the large nuclear charges of Ag and Te atoms, AgTe exhibits a certain Rashba splitting effect in its band structure, making it an ideal platform for studying band splitting. Silver antimonide (Ag₂Sb), on the other hand, displays the metallic electrical properties expected of an alloy, and its band structure also exhibits a certain Rashba splitting effect. If monolithic integration of these two materials can be achieved to construct a high-quality two-dimensional lateral heterojunction, it is hoped that the advantages of both can be combined to generate novel interfacial physics phenomena, such as unique band alignment, efficient charge transfer, or the realization of ohmic contacts between metals and semiconductors. This could provide a new material basis for developing ultra-high-speed, low-power nanodevices.

[0004] However, due to the complexity of the Ag-Sb-Te multi-component phase diagram and the significant differences in chemical reactivity among its components, precisely controlling its nucleation and growth kinetics at the atomic scale to achieve the controllable preparation of lattice-matched, interface-clear two-dimensional Ag2Sb-AgTe lateral heterojunctions remains a highly challenging technical problem in the field. Therefore, developing a method for the efficient synthesis of this novel heterojunction is particularly important and urgent. Summary of the Invention

[0005] The purpose of this invention is to provide a large-area Ag2Sb-AgTe lateral heterojunction, its preparation method, and its application. The prepared Ag2Sb-AgTe lateral heterojunction has a well-defined hetero-edge structure and a large area, greater than 100 nm. 2 It is a planar six-membered ring structure composed of Ag2Sb and AgTe connected by covalent bonds, and has no byproducts.

[0006] To achieve the above objectives, this invention provides a method for preparing a large-area Ag2Sb-AgTe lateral heterojunction, comprising the following steps: S1. Sputtering process is performed on the silver substrate, followed by heating and heat preservation to obtain a silver single crystal substrate; S2. Evaporate and deposit tellurium powder onto the silver single crystal substrate obtained in S1 to obtain a silver single crystal substrate with tellurium clusters deposited. S3. The silver single crystal substrate with tellurium clusters obtained in S2 is heated for the first time and kept at the temperature to obtain a substrate with tellurium silver alloy deposited. S4. Antimony powder is evaporated and deposited on the substrate with tellurium-silver alloy deposited in S3 to obtain a substrate with antimony clusters and tellurium-silver alloy deposited. S5. The substrate with antimony clusters and tellurium-silver alloy deposited in S4 is heated a second time and kept warm to obtain a large-area Ag2Sb-AgTe lateral heterojunction.

[0007] Preferably, in S1, sputtering is performed using argon ion sputtering within an ultra-high vacuum cavity.

[0008] Preferably, in S1, the heating temperature is 400-500℃ and the holding time is 10-30min.

[0009] Preferably, in S2, the evaporation temperature of the tellurium powder is 150-200℃, the temperature of the silver single crystal substrate during deposition is 20-40℃, and the deposition time is 1-5 min.

[0010] Preferably, in step S3, the first heating is performed to 280-320℃, and the holding time is 20-40 minutes.

[0011] Preferably, in S4, the evaporation temperature of the antimony powder is 240-300℃, the substrate temperature on which the tellurium-silver alloy is deposited is 20-40℃, and the deposition time is 1-5 min.

[0012] Preferably, in step S5, the second heating is performed to 180-220℃, and the holding time is 20-40 minutes.

[0013] Preferably, the mass ratio of tellurium powder to antimony powder is 1:1.

[0014] A large-area Ag2Sb-AgTe lateral heterojunction was prepared using the method described above for preparing a large-area Ag2Sb-AgTe lateral heterojunction.

[0015] A large-area Ag2Sb-AgTe lateral heterojunction is applied in the fabrication of photodetectors, photoelectric sensors, photocatalysts, and optoelectronic devices.

[0016] Therefore, the present invention employs the above-mentioned large-area Ag2Sb-AgTe lateral heterojunction, its preparation method, and its application, and its beneficial effects are as follows: 1. The Ag2Sb-AgTe lateral heterojunction prepared by this invention has a well-defined hetero-edge structure with a large area, greater than 100 nm. 2 It is a planar six-membered ring structure composed of Ag2Sb and AgTe connected by covalent bonds, and has no byproducts; 2. The preparation method provided by the present invention involves depositing tellurium powder onto the surface of a silver single crystal substrate to obtain a silver single crystal substrate with tellurium clusters deposited. After heating to the growth temperature of silver-tellurium alloy, an annealing treatment is performed. Then, antimony powder is deposited onto the surface of the substrate with tellurium-silver alloy deposited. After heating to the growth temperature of Ag2Sb, an annealing treatment is performed, and finally a large-area Ag2Sb-AgTe lateral heterojunction is obtained. 3. In this invention, since both tellurium atoms and antimony atoms react with the silver single crystal substrate to form an alloy, and the interaction between Ag-Sb atoms is greater than that between Ag-Te atoms, Sb will replace Te in the Ag-Te alloy, resulting in a Te concentration portion of Ag2Sb-AgTe lateral heterojunction.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a scanning tunneling microscope image of a large-area Ag2Sb-AgTe lateral heterojunction according to the present invention; Figure 2 This is a scanning tunneling microscope atomic resolution image of a large-area Ag2Sb-AgTe lateral heterojunction according to the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0020] This invention provides a method for preparing a large-area Ag2Sb-AgTe lateral heterojunction, comprising the following steps: S1. Sputtering process is performed on the silver substrate, followed by heating and heat preservation to obtain a silver single crystal substrate; S2. Evaporate and deposit tellurium powder onto the silver single crystal substrate obtained in S1 to obtain a silver single crystal substrate with tellurium clusters deposited. S3. The silver single crystal substrate with tellurium clusters obtained in S2 is heated for the first time and kept at the temperature to obtain a substrate with tellurium silver alloy deposited. S4. Antimony powder is evaporated and deposited on the substrate with tellurium-silver alloy deposited in S3 to obtain a substrate with antimony clusters and tellurium-silver alloy deposited. S5. The substrate with antimony clusters and tellurium-silver alloy deposited in S4 is heated a second time and kept warm to obtain a large-area Ag2Sb-AgTe lateral heterojunction.

[0021] In some embodiments of the present invention, in S1, sputtering is performed using argon-ion sputtering within an ultra-high vacuum chamber. Argon-ion sputtering effectively cleans the silver surface, removing oxides and contaminants. The ultra-high vacuum environment prevents recontamination, ensuring the surface purity and atomic-level flatness of the silver single-crystal substrate, thus providing an ideal substrate for subsequent deposition.

[0022] In some embodiments of the present invention, in S1, the heating temperature is 400-500℃, and the holding time is 10-30 min. This promotes the diffusion and rearrangement of silver atoms, forming an ordered single-crystal structure, optimizing the crystal quality of the silver single-crystal substrate, and improving the interface quality of the heterojunction.

[0023] In some embodiments of the present invention, in S2, the evaporation temperature of tellurium powder is 150-200°C, the temperature of the silver single-crystal substrate during deposition is 20-40°C, and the deposition time is 1-5 minutes. Controlling the evaporation rate and deposition amount of tellurium avoids excessive aggregation, forming uniform tellurium clusters, and ensuring that tellurium is uniformly distributed on the silver surface.

[0024] In some embodiments of the present invention, in step S3, the temperature is first raised to 280-320°C and held for 20-40 minutes. Heating to the growth temperature of the tellurium-silver alloy causes a solid-state reaction between tellurium and silver to form a tellurium-silver alloy, achieving alloying of tellurium and silver, forming a heterojunction phase, and providing a reaction interface for antimony deposition.

[0025] In some embodiments of the present invention, in step S4, the evaporation temperature of the antimony powder is 240-300°C, the substrate temperature on which the tellurium-silver alloy is deposited is 20-40°C, and the deposition time is 1-5 minutes. The principle is to control the antimony deposition conditions so that antimony clusters are uniformly formed on the surface of the tellurium-silver alloy without prematurely reacting with tellurium, for subsequent reaction with the tellurium-silver alloy to form Ag₂Sb.

[0026] In some embodiments of the present invention, in step S5, the second heating is performed to 180-220°C, and the holding time is 20-40 minutes. Heating to the growth temperature of Ag2Sb promotes the reaction between antimony and tellurium silver alloy to form two phases, Ag2Sb and AgTe, and a heterojunction is formed through lateral growth, thus completing the construction of the heterojunction and ensuring the stability of the interface between the two phases.

[0027] In some embodiments of the present invention, the mass ratio of tellurium powder to antimony powder is 1:1. Excess or deficiency is avoided to ensure the formation of both Ag₂Sb and AgTe phases.

[0028] Test instruments and equipment: Cryogenic scanning tunneling microscope: purchased from Omicron GmbH, Germany.

[0029] K-cell molecular evaporation source: purchased from Omicron, Germany.

[0030] Argon ion gun: purchased from Omicron, Germany.

[0031] raw material: Tellurium powder: purchased from Sigma-Aldrich, purity 99.9%.

[0032] Antimony powder: purchased from Alfa Aesar, purity 99.999%.

[0033] Silver single crystal: purchased from MaTecK, purity 99.999%.

[0034] Example 1 S1. Sputtering silver substrate with argon ions in an ultra-high vacuum chamber, heating to 450℃ and holding for 10-30 minutes to obtain silver single crystal substrate.

[0035] S2 and 500mg tellurium powder were evaporated and deposited on the silver single crystal substrate obtained in 50g S1 using a thermally resistive K-cell molecular evaporation source at an evaporation temperature of 175℃. The deposition time was 2min, and the temperature of the silver single crystal substrate obtained in S1 during deposition was 30℃, resulting in a silver single crystal substrate with tellurium clusters deposited.

[0036] S3. The silver single crystal substrate with tellurium clusters obtained in S2 is heated to 300℃ for the first time and held for 30 minutes to obtain a substrate with tellurium silver alloy deposited.

[0037] S4. Using a thermally resistive K-cell molecular evaporation source, 500 mg of antimony powder was evaporated and deposited on the substrate with tellurium-silver alloy deposited in S3 at an evaporation temperature of 250 °C for 2 min. The temperature of the substrate with tellurium-silver alloy deposited in S3 during deposition was 30 °C, resulting in a substrate with antimony clusters and tellurium-silver alloy deposited.

[0038] S5. The substrate with antimony clusters and tellurium-silver alloy deposited in S4 is heated to 200℃ for a second time and held for 30 minutes to obtain a large-area Ag2Sb-AgTe lateral heterojunction.

[0039] Example 2 S1. Sputtering silver substrate with argon ions in an ultra-high vacuum chamber, heating to 450℃ and holding for 10-30 minutes to obtain silver single crystal substrate.

[0040] S2 and 500mg tellurium powder were evaporated and deposited on the silver single crystal substrate obtained in 50g S1 using a thermally resistive K-cell molecular evaporation source at an evaporation temperature of 175℃. The deposition time was 3min, and the temperature of the silver single crystal substrate obtained in S1 during deposition was 30℃, resulting in a silver single crystal substrate with tellurium clusters deposited.

[0041] S3. The silver single crystal substrate with tellurium clusters obtained in S2 is heated to 300℃ for the first time and held for 30 minutes to obtain a substrate with tellurium silver alloy deposited.

[0042] S4. Using a thermally resistive K-cell molecular evaporation source, 500 mg of antimony powder was evaporated and deposited on the substrate with tellurium-silver alloy obtained in S3 at an evaporation temperature of 250 °C for 3 min. During deposition, the temperature of the substrate with tellurium-silver alloy obtained in S3 was 30 °C, resulting in a substrate with antimony clusters and tellurium-silver alloy deposited.

[0043] S5. The substrate with antimony clusters and tellurium-silver alloy deposited in S4 is heated to 200℃ for a second time and held for 30 minutes to obtain a large-area Ag2Sb-AgTe lateral heterojunction.

[0044] Example 3 S1. Sputtering silver substrate with argon ions in an ultra-high vacuum chamber, heating to 450℃ and holding for 10-30 minutes to obtain silver single crystal substrate.

[0045] S2 and 500mg tellurium powder were evaporated and deposited on the silver single crystal substrate obtained in 50g S1 using a thermally resistive K-cell molecular evaporation source at an evaporation temperature of 175℃. The deposition time was 4min, and the temperature of the silver single crystal substrate obtained in S1 during deposition was 30℃, resulting in a silver single crystal substrate with tellurium clusters deposited.

[0046] S3. The silver single crystal substrate with tellurium clusters obtained in S2 is heated to 300℃ for the first time and held for 30 minutes to obtain a substrate with tellurium silver alloy deposited.

[0047] S4. Using a thermally resistive K-cell molecular evaporation source, 500 mg of antimony powder was evaporated and deposited on the substrate with tellurium-silver alloy obtained in S3 at an evaporation temperature of 250 °C for 4 min. The temperature of the substrate with tellurium-silver alloy obtained in S3 during deposition was 30 °C, resulting in a substrate with antimony clusters and tellurium-silver alloy deposited.

[0048] S5. The substrate with antimony clusters and tellurium-silver alloy deposited in S4 is heated to 200℃ for a second time and held for 30 minutes to obtain a large-area Ag2Sb-AgTe lateral heterojunction.

[0049] Test case The scanning tunneling microscope (STM) was used to test the large-area Ag2Sb-AgTe lateral heterojunction obtained in Example 1. The resulting STM images are shown below. Figure 1 As shown, a large-area Ag2Sb-AgTe lateral heterostructure was prepared in Example 1. The obtained scanning tunneling microscope atomic resolution image is shown below. Figure 2 As shown, it can be seen that a transverse heterojunction of Ag2Sb-AgTe was prepared.

[0050] Therefore, this invention employs the aforementioned large-area Ag2Sb-AgTe lateral heterojunction, its preparation method, and its application. The resulting Ag2Sb-AgTe lateral heterojunction exhibits a well-defined heteroelement structure and a large area, exceeding 100 nm. 2 It is a planar six-membered ring structure composed of Ag2Sb and AgTe connected by covalent bonds, and has no byproducts.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a large-area Ag2Sb-AgTe lateral heterojunction, characterized in that: Includes the following steps, S1. Sputtering process is performed on the silver substrate, followed by heating and heat preservation to obtain a silver single crystal substrate; S2. Evaporate and deposit tellurium powder onto the silver single crystal substrate obtained in S1 to obtain a silver single crystal substrate with tellurium clusters deposited. S3. The silver single crystal substrate with tellurium clusters obtained in S2 is heated for the first time and kept at the temperature to obtain a substrate with tellurium silver alloy deposited. S4. Antimony powder is evaporated and deposited on the substrate with tellurium-silver alloy deposited in S3 to obtain a substrate with antimony clusters and tellurium-silver alloy deposited. S5. The substrate with antimony clusters and tellurium-silver alloy deposited in S4 is heated a second time and kept warm to obtain a large-area Ag2Sb-AgTe lateral heterojunction.

2. The method for preparing a large-area Ag2Sb-AgTe lateral heterojunction according to claim 1, characterized in that: In S1, sputtering is performed using argon ion sputtering within an ultra-high vacuum chamber.

3. The method for preparing a large-area Ag2Sb-AgTe lateral heterojunction according to claim 1, characterized in that: In S1, the heating temperature is 400-500℃, and the holding time is 10-30 minutes.

4. The method for preparing a large-area Ag2Sb-AgTe lateral heterojunction according to claim 1, characterized in that: In S2, the evaporation temperature of tellurium powder is 150-200℃, the temperature of the silver single crystal substrate during deposition is 20-40℃, and the deposition time is 1-5 min.

5. The method for preparing a large-area Ag2Sb-AgTe lateral heterojunction according to claim 1, characterized in that: In S3, the first heating is to 280-320℃, and the holding time is 20-40 minutes.

6. The method for preparing a large-area Ag2Sb-AgTe lateral heterojunction according to claim 1, characterized in that: In S4, the evaporation temperature of antimony powder is 240-300℃, the substrate temperature on which tellurium-silver alloy is deposited is 20-40℃, and the deposition time is 1-5 min.

7. The method for preparing a large-area Ag2Sb-AgTe lateral heterojunction according to claim 1, characterized in that: In S5, the temperature is raised to 180-220℃ for the second time, and the holding time is 20-40 minutes.

8. The method for preparing a large-area Ag2Sb-AgTe lateral heterojunction according to claim 1, characterized in that: The mass ratio of tellurium powder to antimony powder is 1:

1.

9. A large-area Ag2Sb-AgTe transverse heterojunction, characterized in that: It was prepared using the method for preparing a large-area Ag2Sb-AgTe lateral heterojunction as described in any one of claims 1-8.

10. An application of a large-area Ag2Sb-AgTe lateral heterojunction, characterized in that: The large-area Ag2Sb-AgTe lateral heterojunction described in claim 9 is used in the fabrication of photodetectors, photoelectric sensors, photocatalysts, and optoelectronic devices.

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